The proposed research investigates a biomimetic modular polymer design as a new strategy to achieve advanced biomaterials. The broad, long-term objective of this research is to develop rational design of biomaterials having high order structures for advanced properties. A specific challenge in biomaterials research is to design a polymer that has a combination of mechanical strength, fracture toughness, and elasticity - three fundamental mechanical properties that are highly desired but usually exclusive to each other in polymeric materials. Many structural biopolymers, such as the muscle protein titin, employ modular domain structures to achieve the combination of these three fundamental mechanical properties in one system. We propose to mimic the modular domain design in synthetic biomaterials. Specifically, we propose to synthesize and investigate biomimetic modular polymers having the following modules: (1) quadruple hydrogen bonding modules, (2) peptidomimetic beta-sheet modules, and (3) small protein modules. Our hypothesis is that the introduction of well-defined modular domain structures into synthetic biopolymers should lead to biomaterials having a combination of mechanical strength, toughness, and elasticity. Whereas numerous biomedical applications can be envisioned for this type of biomaterial, this proposal is focused on developing model polymers having modular domain structures with which to study the fundamental structure-property correlation in synthetic biomaterials. Through the proposed studies the following specific aims will be accomplished: (1) Synthesis and studies on discrete oligomers and polymers using well defined quadruple hydrogen bonding modules; (2) Synthesis and studies on discrete oligomers and polymers containing peptidomimetic a-sheet modules; (3) Synthesis and studies on discrete oligomers and polymers using protein G domain III (PG3) as module; and (4) Systematic investigation on the mechanical properties of the discrete oligomers as well as the high mass polymers made from the above modules at single-molecule, nanoscopic and macroscopic levels.